The present invention relates to a vehicle pinion shaft support system (pinion shaft supporting device for vehicle or automobile) and more particularly to, for example, a vehicle pinion shaft support system such as used at a differential (differential gear, differential deice etc.) and a transaxle (differential transaxle, transaxle device, transaxle apparatus etc.).
As a conventional vehicle pinion shaft support system, there exists a vehicle pinion shaft support system such as described in JP-A-8-247260 (Patent Document No. 1).
The vehicle pinion shaft support system includes a pinion shaft, two tapered roller bearings which are provided on the pinion shaft in such a manner as to be spaced apart from each other at a predetermined interval and a pinion ring which meshes with the pinion shaft.
Each of the two tapered roller bearings has an inner race, an outer race and tapered rollers disposed between the inner race and the outer race. The inner race has a large rib face (back face rib) on which large-diameter end faces of the tapered rollers slide. A predetermined initial pre-load is applied to each of the two tapered roller bearings in radial and axial directions of the vehicle pinion shaft support system so that the support rigidity of the pinion shaft becomes a predetermined value or more.
In the conventional vehicle pinion shaft support system, however, in the event that the initial pre-load value is set high with a view to increasing the support rigidity of the pinion shaft, a torque needed to drive the two tapered roller bearings is increased, leading to a problem that the running costs of the vehicle pinion shaft support system are, in turn, increased.
On the other hand, in the event that the initial pre-load is set to a proper value or a value that is lower than the proper value, the value of the pre-load is decreased by a wear generated mainly between the large-diameter end faces of the tapered rollers and the large rib face of the inner races whereby the support rigidity of the pinion shaft by the tapered rollers becomes lower than a predetermined value, leading to a problem that vibration and looseness are generated between the pinion shaft and the tapered rollers.
Patent Document No. 1: JP-A-8-247260